Advertisements
Advertisements
प्रश्न
The filament of a bulb takes a current 100 mA when potential difference across it is 0.2 V. When the potential difference across it becomes 1.0 V, the current becomes 400 mA. Calculate the resistance of filament in each case and account for the difference.
Advertisements
उत्तर
According to Ohm's law,
V = IR
∴ R = `"V"/"I"`
`therefore "R"_1 = "V"_1/"I"_1`
= `0.2/0.1 = 2 Omega`
Similarly ,
`"R"_2 = "V"_2/"I"_2`
= `1/0.4`
= 2.5 Ω
Resistance of the wire increases with increase in temperature. So the difference arises because the temperature of the filament increased.
APPEARS IN
संबंधित प्रश्न
Find the resistance of a conductor if 0.24 A current is passing through it and a potential difference of 24 V is applied across it.
An electrical bulb is marked 200V, 100W. Calculate the electrical resistance of its filament. If five such
bulbs are connected in series to a 200V supply, how much current will flow through them?
How should the two resistances of 2 ohms each be connected so as to produce an equivalent resistance of 1 ohm?
In the circuit shown in the figure, find the total resistance of the circuit and the current in the arm AD.
Answer the following question.
Distinguish between Ohmic and non-ohmic substances; explain with the help of example.
State macroscopic form of Ohm’s law.
Calculate the total resistance of the circuit and find the total current in the circuit.
Two cells of same emf E but internal resistance r1 and r2 are connected in series to an external resistor R (Figure). What should be the value of R so that the potential difference across the terminals of the first cell becomes zero.
Vinita and Ahmed demonstrated a circuit that operates the two headlights and the two sidelights of a car, in their school exhibition. Based on their demonstrated circuit, answer the following questions.
- State what happens when switch A is connected to:
a) Position 2
b) Position 3 - Find the potential difference across each lamp when lit.
- Calculate the current.
a) in each 12 Ω lamp when lit.
b) In each 4 Ω lamp when lit.
OR - Show, with calculations, which type of lamp, 4.0 Ω or 12 Ω, has the higher power.
The voltage - current readings of a certain material are shown in the table given below:
| Voltage (V) | 10 V | 20 V | 30 V |
| Current (I) | 2 A | 3 A | 4 A |
Study the table.
- State whether the conductor used is ohmic or non-ohmic.
- Justify your answer.
- State Ohm's law.
